Evangelos Achillopoulos
Well-known member
- Joined
- Apr 10, 2007
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- 558
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- Location
- Athens, Greece
- Website
- www.motionfx.gr
The defacto standard for years on film out is the Cineon 10bit Log files.
When we want to scan film, we using the Cineon format or the DPX variant in which the code values are between 0 and 1023 (with black point 95 and 90% reflectance white to 685). Cineon format is designed to compress 14bit -16bit linear light values to 10bit Log.
The problem is the following:
We had a test shot today for a big spec spot ad, tomorrow we will do the actual shooting with three RED’s, using the latest firmware ver.15. The test footage that we shot was having deep blacks and just clipping whites. Because we will filmout the final cut, of the ad, to camera negative, I requested the whole workflow to be in Log 10bit DPX, in order to preserve the full information captured by the camera.
When I export the sequence from RedCine using the PDLog685, I noticed that the histogram was limited between 95 and 685 code values, which was very weird to me, since I have a great experience of what a good histogram is (because of my film DI experience), when it’s properly encoded to Log.
I tried to change the ASA from 100 to 320, in order to boost the highlights, and instead, to have the brightest white above 685 code value, RedCine squeeze all the white area just below or exactly in 685 value, so all the highlights ware clipped!
Normally it should be possible to send the white above 685, with NO clipping!
And that’s typical… The 685 white point, it’s just the 90% reflectance white. There are reflectance or scene brightness well above 90% in real life…
The following table shows some of the valid code values of Cineon in respect of light reflectance and negative film density.
As it’s being evidenced from the above table cineon values are NOT limited to 685 value.
When using RedCine to export Cineon Log encoded DPX files the only selection is PDLog685.
The PDlog985 is not an option, since what it’s doing its just expands the white value, so when the white was on 685 now it’s being lifted to 985, and still clips everything.
Actually its very difficult to clip DPX 10bit Log, almost impossible, I personally haven’t seen higher value than 950 even with Fujifilm Eterna 500, which has more than14 stops latitude… so why REDcine clips in 10bit Log?
What’s wrong?
Why can’t we have a proper full Cineon Log space from RedCine?
Graeme, Lucas (Assimilate) please explain. Am I wrong?
When we want to scan film, we using the Cineon format or the DPX variant in which the code values are between 0 and 1023 (with black point 95 and 90% reflectance white to 685). Cineon format is designed to compress 14bit -16bit linear light values to 10bit Log.
The problem is the following:
We had a test shot today for a big spec spot ad, tomorrow we will do the actual shooting with three RED’s, using the latest firmware ver.15. The test footage that we shot was having deep blacks and just clipping whites. Because we will filmout the final cut, of the ad, to camera negative, I requested the whole workflow to be in Log 10bit DPX, in order to preserve the full information captured by the camera.
When I export the sequence from RedCine using the PDLog685, I noticed that the histogram was limited between 95 and 685 code values, which was very weird to me, since I have a great experience of what a good histogram is (because of my film DI experience), when it’s properly encoded to Log.
I tried to change the ASA from 100 to 320, in order to boost the highlights, and instead, to have the brightest white above 685 code value, RedCine squeeze all the white area just below or exactly in 685 value, so all the highlights ware clipped!
Normally it should be possible to send the white above 685, with NO clipping!
And that’s typical… The 685 white point, it’s just the 90% reflectance white. There are reflectance or scene brightness well above 90% in real life…
The following table shows some of the valid code values of Cineon in respect of light reflectance and negative film density.
HTML:
Scene Negative Cineon
Brightness Film Code
(reflectance) Density Value
1% 0.00 95
1% 0.01 102
1% 0.02 107
1% 0.05 122
2% 0.11 151
2% 0.17 180
3% 0.23 212 Kodak gray card Black patch
4% 0.30 244
5% 0.36 277
6% 0.43 309
7% 0.49 341
9% 0.56 373
11% 0.62 406
14% 0.69 438
18% 0.75 470 Kodak gray card Gray patch
23% 0.81 501
29% 0.87 531
36% 0.93 562
45% 1.00 593
57% 1.06 624
72% 1.12 654
91% 1.18 685 Kodak gray card White patch
114% 1.24 716
144% 1.30 746
181% 1.36 777
229% 1.43 808
288% 1.49 839
363% 1.55 869
457% 1.61 900
As it’s being evidenced from the above table cineon values are NOT limited to 685 value.
When using RedCine to export Cineon Log encoded DPX files the only selection is PDLog685.
The PDlog985 is not an option, since what it’s doing its just expands the white value, so when the white was on 685 now it’s being lifted to 985, and still clips everything.
Actually its very difficult to clip DPX 10bit Log, almost impossible, I personally haven’t seen higher value than 950 even with Fujifilm Eterna 500, which has more than14 stops latitude… so why REDcine clips in 10bit Log?
What’s wrong?
Why can’t we have a proper full Cineon Log space from RedCine?
Graeme, Lucas (Assimilate) please explain. Am I wrong?